I've got a 1980 Motobecane with Shimano 600 derailers. The chain makes a reasonable about of noise (from the rear derailer/tensioner area), but I don't know what's normal or what to expect from a bike this age. I realize you can't hear it so I can't tell you exactly how loud it is... I can hear it when I'm riding if there's no traffic around, otherwise it drowns out. The rear is indexed, so could it just be an adjustment thing?